Basically, this is the tool to recommend to newcomers when they ask questions about fees. Existing tools are either too complex with too many numbers or have a tendency to overestimate fees.
newcomers MUST NOT use a website to estimate their fees. they must always choose a good wallet and trust that it gives them the best fee suggestions.
and what you call complication is a requirement because it is complicated to analyze the memory pool and come up with the appropriate fee estimation.
additionally your website is not that accurate either. it also is overestimating the fees. for instance it currently suggest 51 satoshi/vbyte takes 2 hours whereas that price is around the level where you would get a high priority transaction and get confirmed within next block (hence ~10 min) and the suggested 89 for high priority is already way too much.
also you seem to be using virtual bytes for size but limit the max to 1 MB (if i understand your tables correctly!) which is false because the maximum block weight is 4 MB.
This.
The fee depends on how many inputs you are using. If you are trying to send a transaction that is made up of dust, it will be expensive.